Age-related decline in the quality or soundness of human sleep is being assessed by comparing the auditory awakening threshold in all EEG stages in young and elderly sleepers. Whether the awakening threshold in Stage 4 sleep in the elderly remains deeper than in other stages despite decline in Stage 4 amplitude will be assessed, along with an evaluation of the effect of exercise on the soundness of sleep in the elderly. Also to be examined in the elderly are relationships of insomnia with the level of physiological arousal during sleep, the effect of exercise on sleep disturbance, and relationships among sleep, exercise, and morale.